Utilizing citizen science to document a mange epidemic in western gray squirrels in California

Abstract

Citizen science allows for economical collection of data across large geographic areas. However the degree of expertise required, inter-observer consistency, and strategies for compiling and disseminating results may affect the quality of the project data. We used citizen science to recreate spatio-temporal characteristics of an outbreak of notoedric mange (Notoedres centrifera) in western gray squirrels (Sciurus griseus anthonyi) in the San Bernardino Mountains of California, USA, and evaluated strengths and limitations of citizen science to collect these data. In June 2012, we deployed an online survey asking local residents to record location, date, and details of past squirrel sightings (prior to the epidemic), and recent sightings of sick and healthy squirrels. Respondents provided 160 historical observations, 83.8% of which had sufficient information for inclusion. Although there was an eventual decay in reporting, these data allowed us to detect spatial clusters of mange, a west to east spread, and the presence of some unaffected squirrels after the epidemic. Respondents reported mange cases earlier than rehabilitators and at least a year ahead of a noticeable decline, while 76.3% observed the decline after 2010. Residents who lived in the study area for more than half the year were 2.3 times more likely to observe a gray squirrel with mange. After the start of the survey, there were 6 reports of gray squirrels with signs suggestive of mange but 188 reports of healthy gray squirrels, indicating the peak of infection in this mange epidemic was over by 2012. © 2016 The Wildlife Society.